Sunday, January 14, 2018

Why BIM Needs Integrated Project Delivery

I have been learning this business for 29 years. As I transition to retirement, I get reflective and annoyed. Annoyed, because certain things do not get better; they may be getting worse.

Recently I bid (on behalf of Cary Concrete Products) on some simple precast panels for a retaining wall (a.k.a. lagging panels or soldier piles). I have done a few similar projects. Therefore I know a little, though not much, about them. If you are unfamiliar with these structures, search for “lagging panel” or “soldier piles” (see figure 1). They hold back dirt.

Figure 1: Examples of retaining walls

The bid documents were created by a very large multi-national design firm. The plan section of one drawing showed a detail I had never seen before (see figure 2). The intent was clear: to visually cover up vertical H-beams.

Figure 2: Original detail drawing, plan section

But to my knowledge, the detail smelled of serious installation and constructability problems, and would likely suffer from durability problems, as well:

The design does not reflect real life tolerances for placing the piles. The steel H-beam is pounded into the ground; the slot in the concrete panel is much smaller than the pile-to-pile variance.

The front face will never have good panel-to-panel alignment.

The concrete panel holds back dirt, and the forces from that get concentrated on the thin portion of the panel that presses against the steel.

If the tab does not crack initially from soil loads, then over time as the steel corrodes and expands it may crack the tab. Once the concrete starts to crack, water gets into the crack and subsequent freeze-thaw cycles will cause further deterioration of the concrete, leading to the eventual failure of the whole system. It will take many years, but likely be much quicker than the life expectancy by the design.

I called a general contractor bidder I knew to be highly experienced with this type of wall. He concurred that the detail was borderline nightmarish. I then found five further confusions or errors in the bid documents pertaining just to the precast structures -- what about the rest of the project? I summarized the main problem by asking, "Has the use of the slot been fully engineered, and is there a known example where it was both successfully installed and remained durable?"

Subsequently one of the many addenda issued to the bid documents featured a different detail (see figure 3). The revised detail was new to the project and obviously new to the original designers, but not new to anyone with experience building piles; in fact, it is common. It hides the steel from view but without all the real-world complexities of the original slotted precast. It transfers load from the panel to the steel where the panel is strong (close to full thickness)

Figure 3: Revised detail drawing

Lessons Learned

What lessons are implicit in this situation?

Designers sometimes wing it. They may have no idea of the best way to solve a problem. They are under the gun to get drawings out, so they just take a stab at it. Not uncommon in my experience.

Contractors are the designers’ proofreaders. The pre-bid questions and subsequent RFIs [requests for information] are made by people with more knowledge in checking and commenting on the work than those who are actually paid to design -- but have less knowledge of specific materials, such as precast concrete or its interface with steel beams. The cost of all these people-with-relevant-knowledge reviewing the work of those-with-limited-knowledge never shows up as a design cost; it is included in the overhead of every bidder.

Once upon a time, there was a Master Architect. Everyone I know who has worked from historic drawings (75 years or older) is impressed with the level of detail and precision, and how the drawings generally match what was built. Today, however, it no longer is possible for an architect to have deep knowledge of what they are designing, and there are good reasons for this:

The huge variety of materials available, each with its own variants and considerations; a typical project today has 10,000 - 12,000 products

Change does not stop, and so new products and new construction techniques emerge regularly

Building codes are way more complicated than they used to be

Expectations for speed have accelerated

Somewhat surprising to me is how little the design process has changed, given how much the reality has changed.

Big name = big size + good marketing. To stay big, big firms have to be good at getting lots of work. The firm may have a world-class expert in one of its offices, but that knowledge may never make it to a project, as in this case. In contrast, small boutique firms often bring much deeper knowledge directly to the table. Owners are not in a position to assess the expertise of the people assigned to design the project.

The drawings I showed here were made by a design firm considered to be a leader in “knowledge management”; what must the laggards look like? This phenomenon is not unique to construction. Many small independents are much better at doing the work, but not at marketing themselves.

IPD is critical to the success of BIM. The enormous complexity of construction is not obvious to people who are not intimately involved with actually building the design. A model that does not reflect deep, usable knowledge does not contribute to efficient construction. This was recognized with the early experiences with BIM [building information modeling]. Problems led to the incorporation of IPD [integrated project delivery].

Knowledge has to come from somewhere. Subcontractors have deep expertise and are financially committed to the project, and IPD is a method to bring them to the process much earlier than the design-bid-build process does. IPD was not originally tied in with BIM, but today the two should be tightly coupled.

We are still far from having knowledge embedded in design tools. This is not clear when you listen only to people who want to sell you their software. But IPD is a method for efficiently transferring knowledge from people’s heads (where in large part it still resides) to the design.

More More News

"Everyone wants to control your life: Google, Apple, Amazon...everyone. It's what I've been calling the feudal Internet. I fear it's going to get a lot worse" (Bruce Schneier). How will the tech backlash, which began in 2017, affect CAD vendors in 2018?

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IronCAD 2018's new Bulk Drawing Creation transforms 3D views into 2D drawings and sheets automatically with predefined templates. I've seen the demo, and it is impressive. I don't think any other CAD package is doing this. All new 2018 features are here: http://www.ironcad.com/blog/ironcad-2018

Letters to the Editor

Re: Autodesk Subscriptions

Still using the old mechanical desktop for my small business. I think I bought it late 1990s. It's on a DVD with codes to install. Had to reinstall Windows XP and disconnect my CAD computer from the Internet to keep it working.

As little as I use it I could not justify a yearly subscription. Software companies have gone insane the last 5 years, including Microsoft. Well, the good thing is it will bring competitors. Linux has come a long way the last 5 years. Maybe there is hope. - D Decker (via WorldCAD Access)

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I'm a sole owner-operator. My AutoCAD 2005 still works on Windows 10 but slowly and with a few glitches. I got 12 years out of it, and now finally, I am using another CAD software.

I work for myself, not Autodesk. Bye-bye Autodesk! - Thirty-two year user (via WorldCAD Access)

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